Angelina Jolie has condemned a US church's threat to burn copies of the Muslim holy book to mark the ninth anniversary of the September 11 attacks.

The 35-year-old actress spoke out during a trip to Pakistan to raise awareness about the floods.

"I have hardly the words that somebody would do that to somebody's religious book," Angelina told reporters in Islamabad.

The actress spoke out about the proposed burning by a Florida church after visiting refugee camps in northwestern Pakistan - one of the areas of the country hit hardest by the floods.

She visited the largely Muslim country in her capacity as a goodwill ambassador for the UN's refugee agency.

The floodwaters in Pakistan have killed more than 1,700 people and have affected over 18 million others.

Angelina, who wore a long dress and covered her hair with a black scarf in keeping with local Muslim custom, said: "I was shocked especially by how high the floodwaters went. In some of the people's houses, it was nine feet (three meters) high."